1. Field of the Invention
The present invention relates generally to cameras, and more particularly, change to an improvement in the winding up device of a focal plane shutter in a camera.
2. Description of the Prior Art
In the case of a camera provided with a focal plane shutter, generally the film winding up mechanism is functionally engaged with the shutter winding up mechanism through a series of gears in such a manner that by means of operating a winding up lever the film winding up and shutter winding to a charged position are carried out at the same time. A clutch provided in the series of gears is released at the time of shutter release in such a manner that only the shutter mechanism is rotated along the reverse direction to that at the time of the winding up operation. One end of the shutter plane is fixed on the winding up drum so as to be wound up on the drum at the time of the shutter charge and to be pulled in the inverse direction in order to carry out the opening and closing operation at the time of the shutter release. The running speed of the shutter plane depends upon the strength of a driving spring and the moment of inertia of the rotary bodies such as the winding up drum rotated in functional engagement with the shutter plane, the gears and so on. When the gear series is designed so as to be rotated together with the shutter winding up drum, the running speed of the shutter plane is so low that it is necessary in the short shutter time that the width of the exposure slit formed with the shutter planes should be remarkably small, whereby the shutter efficiency is inferior while the exposure time varies due to a slight error in the slit width while the exposure in every part of the picture can not be uniform. This is inconvenient for obtaining high exposure accuracy of the shutter.